The field of the invention is audio transducers, and particularly, audio transducers for high fidelity headphones used to reproduce stereophonic or quadraphonic program material.
A number of commercially available headphone structures provide the listener with adjustments which allow him to tailor the response of the headphones to his own particular tastes. For example, volume controls have been mounted in the cups of a number of commercially available headphones, such as the Models HV/1LC, K/6LC and K/6LCQ manufactured by the Koss Corporation, to provide the listener with convenient means for adjusting the level of the reproduced sound and for adjusting the balance between channels. Also, means for mixing and phase shifting the audio channels before application to the transducers have been provided in commercially available headphones, such as the Models Phase/2 and Phase/2+2 manufactured by the Koss Corporation, to electronically simulate a variety of listening conditions.
Although listeners universally demand that quality headphones have a broad frequency response, listeners quite often establish very definite tastes with respect to the shape of the frequency response curve within that operating range. The low frequency, or bass response of a quality headphone is adjusted during manufacture by well known acoustic tuning and damping techniques. As a result, a headphone with a relatively "flat" bass response can be constructed, or with proper damping, a headphone with "boosted" bass response can be constructed. A listener may develop a taste for either type of headphone, depending, for example, on the type of program material being reproduced. The devotee of popular music may prefer a headphone with boosted bass response, whereas the connoisseur of classical music may prefer a headphone having a more realistic, flat bass response.